91 200 johnson will not stay running under load

[jonesg]

Re: 91 200 johnson will not stay running under load

The tach needs fixing.
You can't set the idle without knowing the rpm.

 

[ezeke]

Re: 91 200 johnson will not stay running under load

"also, it runs fine on the hose but when it is in the water, it shows its symptoms... when i first put the boat in the water th e last time it seemed to idle fine for about the first 30 seconds then didnt want to stay running especially in gear.."

Your motor has a system called QuikStart that automatically advances the timing when the engine is cold, then releases the timing when the temperature reaches around 96 degrees or when the engine turns higer than 1100 RPM whichever comes first. The timing and idle have to be set with QuikStart disabled, under load.

I think that what is happening is that your idle is set too low once the QuikStart kicks out. As soon as you drop your warm up lever and try to get in gear the engine would die.

When on muffs, there is no load on the system, not even back pressure, so the motor could seem to run fine on as few as three cylinders.

 

[tampaaquasport81]

Re: 91 200 johnson will not stay running under load

im going to try to diagnose the carbs with what faztbullet said, and ezeke, what do i need to do to correct the quickstart? it also tries to quit when revving in neutral as well

 

[jonesg]

Re: 91 200 johnson will not stay running under load

Without a tach you can't do diddly because you have no idea what the idle speed is on a hose or in the water, you can't guess it, you need to set it and know its where it should be.

 

[Faztbullet]

Re: 91 200 johnson will not stay running under load

You are going to have to have a tach to set rpm as suggested. On port head you will see a sensor with 2 wires on the head.A wht/blk wire and a tan, disconnect the wht/blk from pack and on pack side insert a wire in connector and attach it to engine ground ,this will bypass quickstart. Here are pictures of what i am seeing.

 

[CaptRoob]

Re: 91 200 johnson will not stay running under load

holy cow faztbullet. that looks aweful. my motor had all of these same symptoms but after a trip to my local omc tech it has been idling ok and not shutting off at idle. he did a link and sync on the carbs and linkage. replaced some of the plastic linkage parts that were cracked or broken and replaced one bad coil. runs pretty good now and does not shut off but i still get that phifft sneeze out the carbs every 5 seconds or so. my mech told me if it starts idling like crap again and shutting off that the carbs will need to be gone through.

would boysen reeds be any more resistant to ethanol than the factory reeds?

 

[CaptRoob]

Re: 91 200 johnson will not stay running under load

would boysen reeds be any more resistant to ethanol than the factory reeds?

never mind. it seems boysen only sells the reeds and not the reed blocks.

 

[Faztbullet]

Re: 91 200 johnson will not stay running under load

This (reed)problem will be constant no matter what service is performed, it the last thing to check if all else fails to make it quit sneezing. I have also had to go down 2 sizes on the idle jets on older/worn engines to make this stop.

 

[CaptRoob]

Re: 91 200 johnson will not stay running under load

thanks! i really appreciate the info! i'm glad we've got a few good seasoned techs on the forums to point out the not so obvious things that would cause problems! i'll be doing the plug the jet test today before the game!

you da man!

 

[tampaaquasport81]

Re: 91 200 johnson will not stay running under load

just got the reeds out, and they look fine, 2 of the tabs are'n against the cage completely, but doesn;'t look like enogh to stop an engine, but then again what do i know... i had posted earlier that my compression was 75-78psi. and did a decarb and i dont think compression changed, is that compression to low to run my engine? maybe i just need to rebuild the powerhead?